Method for secondary oil recovery



Nov. 4, 1958 w. F; McMAHoN 2,858,890

METHOD ROR SECONDARY OIL RECOVERY Filed March 1e. 1955 2 sheets-sheet 1Nov. 4, 1958 w. F. McMAHoN METHOD FOR SECONDARY OIL RECOVERY 2Sheets-Sheet 2 Filed March 16, 1955 '/lfrlllllf llllllllllllllllllllllIl United States Patent 2,858,890 l Patented N ov. 4, '1958:

ffice METHOD FOR SECONDARY OIL RECOVERY William Frederick McMahon,Riverside, Calif. Application March 16, 1955, Serial No. 494,681 sclaims. (ci. 16a-s) This invention relates to a method for theproduction of natural oil from stagnant pools in subsurface formations,especially those formations inwhich the natural energy has beendepleted.

I have in a series of patents, to wit: Patentv No. 1,642,121, patentedSept. 13, 1927; Patent No. 1,779,483, patented Oct. 28, 1930; Patent No.1,801,520, patented Apr. 21, 1931; Patentv No. 1,992,436, patented Feb.26, 1935; Patent No. 2,080,622, patented Mayl 18, 1937; Patent No.2,080,623, patented May 18, 1937; Patent No. 2,080,624, patented May 18,1937; Patent No. 2,114,905, patented Apr. 19, 1938; Patent No.2,291,911, patented Aug. 4, 1942, disclosed means and devices forraising natural oil from oil wells by employing a uid as a lifting means(hereinafter referred to as the power fluid) under pressure introducedinto a tubing located in the oil well, this fluid intermingled withincoming oil from the oil formation in a high velocity zone, under apressure relatively lower than the formation pressureor less than thesubmergence head of the oil in the oil well above said zone, suchras aventuri-tube, and the intermingled oil and power fluid are circulated tothe surface through a tubing passageway separate from the tubingemployed for the incoming power iluid.

I have now found that if, as the motive uid which is employed in thelifting of the oil, I employ it simultaneously to move oil out ofstagnantpools into the oil well, I obtain surprisingly high rates ofproduction from subsurface oil formations in which the natural energyhas been depleted. v Y

In order to accomplish these results, I circulate the immiscible powerliquid, e. g., Water, from the surface under pressure of the order offifteen hundred pounds per square inch, in oil wells of less than fteenhundred feet deep, throughV two Wells, e. g., an imput Well and anoutput well, simultaneously and continuously causing the commingling ofthe irnmiscible liquid and oillocated in a stagnant pool somewhere inthe formation between the two said wells and causing the oil to be movedout of the said pool and into a throat of a venturi-tube submerged inthe oil in the output well and returning the vcommingled oil and waterto the surface. In the mentioned output well is located the pumpingmeans described in the aforementioned patents.

I heat the said immiscible power liquid to about two hundred thirtydegrees Fahrenheit and circulate about thirty-five gallons per minutethrough tubing connected with the venturi-tube located in the outputwell, and thirty-live gallons per minute into the formation through theimput well.

With these said rates of circulation of liquid I recover about twelve ormore barrels of net oil per hour from the formation.

With the above mentioned temperatures used in the power liquid, the heattransferred to the oil-water stream in the output well containing thejet pump or venturitube is seven hundred fty thousand British thermal`units per hour and the heat loss to the formation, and which 2 serves toheat the formation and area surrounding the output well, is four hundredthousand British thermal units per hour.

In output wells of less than two thousand feet deep, I nd in heating thepower liquid to a temperature of two hundred thirty degrees Fahrenheitand circulating this heated liquid down throughpthe jet pump locateddeep in the output well that, the temperature of the returningcommingling oil and water at the 'surface is about two hundreddegreesFahrenheit or a differential loss of thirty degrees Fahrenheit. p

This said loss of thirty degrees in temperature results in a net loss ofthree hundred fty thousand British thermal units per hour in the outputwell. p

When using this heated water ood repressuring drive to 4cause naturaloil to be moved into the output well' from stagnated conditions or poolsin the formation,

I have found that a considerable quantity of tine sand' is movedsimultaneously with the natural oil into the said output well and I geta surprising increase in the rate-of ow of oil to the surface when Icause this fine sand to be simultaneously and continuously removed fromthe output well with the natural oil, as contrary to an intermittentaction in the removal of said sand and oil. p

I base this increasein oil production on the fact that unless this tinesand, which has a neness similar to that of flour, is immediatelyfandcontinuously removed to the surface together with the oil just as soonas the sand reaches the output well, said sand 'will'build up lin thearea surrounding the said output well and cause rthe oil production tobe either shut olf or'considerably re-y duced. Thusfrom my discovery itis evidentthat many oil wells were heretofore abandoned prematurelybecause 'of the lack of removal and the accumulation of the said neilour like sand in the area surrounding the abandoned oil well andcaused the oil well bore to be shut olf from the formation.

My invention will be yfurther described in connection with the drawings,in which: l f Y Fig. 1 lis a schematic elevation view of the recoversystem, showing the joint piping system and the union relationship oftwo oil wells ljoined together to provide anvintegral unit utilizing asubterranean channel.l Fig. 2 is a sectional elevation through the jetpump. Fig. 3 is a fragmentary sectional elevation at the well head ofthe output well in which is located the jet pump. Fig. 4 is afragmentary sectional elevation at the well head of the input wellthrough which water is fed into a subterranean channel. l Y f .i Fig. 2illustrates 4the form of jet pump described inl detail in Patent No.2,114,905, to which reference mayl be had for more and furtherparticulars of the structure and mechanical operation of the jet pump. Imay use the form of jet pump illustrated in any of the other of mpatents referred to above. .f

I employ the form here illustrated as a convenient eX- ample of amechanical structure in which-the process of my invention may be carriedout, without any intention of limiting the method to said structure,since the method may be carried out in any of the structures disclosedin myv listed patents or in any other structure wherein the immiscible`liquid and oil may be comtional pumping means for reasons to bedescribed below.` An outlet 3 is provided near `the bottom lthereofcon-v trolled by a check valve 4 and connected by linev 5 to the suctionside of pump 7. A main supplyline 8 will be connected to tank 1 tofurnish a supply of water to the suction side of pump 7 from outsidesources such as i f or example, water wells or rivers or oceans and inthis line 8 would be incorporated a lter 9 to eliminate plant life andsea life and oxygen from the water thus used. A suitable chack valve 10is provided in line 8, and

also ai booster pump 1,1 will-be incorporated in line 8 if needed-toraise water from a source well not shown to supply water to the suctionside of pump 7.'

The discharge from pump 7 passes into a main disp charge pipe line 12and then into discharge pipe line 13 leading into the oil formation 14through input well 15 and said discharge also passes into discharge pipeline t 16 which is connected with the jet pump 17 located in the theoutput well 18. n .The line 16is jacketed by the tubing 19 which islconnected to the jet pump 17 and serves to"pr0yide an l annuluspassageway 20 for fluids entrained from the formation 1'4` by theA jetpump 17. This tubing 19 is suspended in the output well 18` byconventional means 21 forming the casing head 22. From this annuluspassageway 2 0 fluids circulatedl by the pump`7 plus all uids en- 1trained from the formation 14 are discharged therefrom 'at the cross 23-into line 24.

t is recirculated tothe pump 7 through line 5 and oil is p withdrawnthrough line 28. A suitable valved 29 cleanout or drain line v30 isprovided in the bottom of tank 1 to flush out the sand separated fromthe water and oil inlank V1'. The sand flushed out of tank 1 is conveyedl by line 30 to=a sump pit'not shown. An automatic bleeder line 3-1maintains a constant water level 32 in tank i1. This bleeder 31 isconnected to the bottom of tank 1 and also to the line 30l leading tothe sump pit above mentioned.

A storagebr shipping tank 32 receives the oil conveyed thereto byline28. i

By referring to'Fig. 1 it will be noted that Ij provideat the outputwell head 22 what is termed in the industry as a christmas. tree 33.lThis so-called christmas tree 33 comprises a series of four plug valves34, 35, 36 and' 37 arranged tofreverse'thefow of fluid'sinto 'the line16 and tubing 19t andi permits, at the` operators will, fluid to bedischarged into the formation 14throughthe jet pump 17 The regulardirection of ilow of discharge from pump 7 intoline16 is made by closingplug valve 34 and opening valvel35 and' closing valve 36 and havingvalve 37 opened. Io reverse the-flow; of the discharge lfrom pump' 7 `sothat the' flow is directed into the annulus passageway 20 IA arrange thesaid' four plug valves thusly, valve-734 opened, valve 35 closed, valve36 openedandy valve `37 closed. Il use this latter valve manipulationwhen cleaning out the output well from sand and/or discharging waterinto -the formation 14 through output well 18. Shouldg the annulus 20become plugged with sand at any time-I simply reverse the ow of fluidffrom pump 7 as just described and clean out the-said annulus 20;

A'pressure gauge 38 lconnected in the christmas tree 33` serves-to showthe pressure set up by thepumpy 7. n

.Referring now tothe jet pump 17 which is located in the= output well 18and to Fig. 2 of the drawings.

Atthe end of tubing 16 and' 19 is positionedl a pumpbody 39; cored orboredvat'40- at one end to produce an linlet bore intoY which thetubingy 19 may be threaded or otherwise secured by ya fluid-tightconnection. The opposite end of the body is likewise bored or coredlat41. The bore41` is closed by a subjoint or'bull plug 42 whichl makes afluid-tight seal in thejbore 41.k The inner face-of the plug 42 forms a'liemispherical surface 43; There is-thus formed a chamber 44Coredpassages 48`r connect chamber 44 with upper chamber 45.` The pumpbody 39 is cored to produce a chamber 46 whichcommunicates with, theformation 14 through the Side wall of pump body `39'. The chamber 46 isseparated from chamber 44 and chamber 45 by a wall.47.

Connected to tubing 16 is a split venturi-tube formed of two axiallyaligned venturi cones 49 and 50 whose nozzles 51 and 52 are spaced fromeach other by a small separation 53 which has direct communication withchamber 46 and formation 14.

Venturi-cones 49 and 50 each have threaded engagement with pump body 39to make a duid-tight seal with the body 39.

The nozzles 51 and 52 are cast of tungsten-carbide material to resistabrasion set up by sand being entrained from the formation 14. Thesenozzles are secured in Venturi-cones 49 and 50 by lead seals 54 in afluid-tight seal construction. These nozzles have direct communicationwith formation 14 through the medium of chamber 46. The discharge oricein nozzle 51 is smaller in diameter than the opposing orifice in nozzle52.

The discharge outlet 55' from cone 50 and nozzle 52 is so positionedthat the axis of the cone is coincident with the vertical radius of thesemispherical cup 43.

The .tubing 19 is of such length that the inlet port 46 is atthe desiredsubmergence below the uid level of the iluid in the bore hole formingthe output well 18';

' The' operation of the un'it is as follows: The hot water is pumped'bypumpv 7 at the desired discharged pressure asreportedv by gage 38 andpasses downwardly through? tubing 16, entersfn'ozzle 51 andy dischargestherefrom lthrough' chamber 53v into the opposite nozzle 52. The fluidsand sand entrained from the formation 14 intermingle with the hotwaterin this nozzle 52 and are discharged at 55 into the chamber 44 of thepump body 39. From chamber' 44 the intermingled' fluids ow upwardthrouglli` passage 48l into the chamber 45 thence upward through theannulus passage 20' to the surface of the earth.

AS1 is explained' in the aforementioned' listed patents, this zone atchamber 53 is the vena contracta of the venturi-tube system and the hotwater being circulated by pump 7 is at its' highest linear velocity, atthis point, of any in the entire system. At this point or chamber 53 thehydrostatic pressure is converted intovelocity and consequently, thepressure inv chamber 53 is low comparednto that at the inlet to the'nozzle 51fro'r at the outlet 55 from nozzle 52. This highest vel'ocitybeing a function of the dynamic head of the water owi'ng in line 1'6 in'relation to the pump 7 discharge pressure'. As the pump pressure isincreased a velocity of hot Water isreached' in the venturi=tub`e whereAthe static head of the-oil in the bore hole 1-8 is suilicient to permitthe oil?, sand and gas to ow throughchamber 53 into nozzle 52 as alsoexplained above.

It will be observed that the commingled fluids in the annulus passage 20vflow in a closed system into' pipe 24 andV out of pipey 5 to andifromtank 1.A A stung' box 59 is provided to seal off the tubing I6 inrelation to tubing 19 to cap the annulus passage 20.

A conventional casing 56 is used in output well 18 and a conventionalcasingl 57 is likewise used in input well 15. BothV of these casingswill be perforated' at the place where the casing contactsy theformation 14. One or more input wells 15 may be used to'supply theoutput well 18. The input well 15 and out'put well 18 will be spacedfrom one hundred feet to three hundred feet apart.

Pump 7 will be a triplexpump construction capable of discharging aboutseventy gallons per minute up to' twenty-five hundred pounds per squareinchpressure and the average pressure used `will be about seventeenhundred4 lifty pounds per suare inch pressure. Therefore operating underseventy gallons per minute discharged into line 12v at seventeen hundredfty poundsper square inch pressure I will use a'ninety horsepowerinternal combustion engine'to drive the pump 7`.

, In theaverage oil well' there may be found enough gas to run thisengine and if so I will use pipe line 58 having connections with theengine, not shown, and the casing's 56 and 57 and also with the tank 1atV the uppermost portions thereof in each case. Otherwise I will usebutane to run this prime mover, or an electric motor may be used in oilelds where electricity is available.

The said seventy gallons per minute of water discharged by pump 7 willbe used to feed the input well pipe 13 to discharge about thirty vegallons per minute into the formation 14 through this input well 15 andthe remaining thirty-tive gallons per minute will be used as a powerfluid or motivating medium in output Well 18 to operate the jet pump 17located therein. I have above described the piping means or system todistribute this said seventy gallons per minute of water, heated in tank1 to about two hundred degrees Fahrenheit, to input well 15 and outputwell 18.

One of the important discoveries I have made to increase the productionof oil is to overcome the present conventional oil eld practice ofproviding means such as gravel pack or the like to hold out sand fromentering into the output well in order that the conventionalreciprocating rod pumps would not become sanded up. I overcome thiserroneous practice by removing the sand as fast as it `comes into theoil well, and I let the sand come freely into the oil well rather thanto hold the sand out from coming into the oil well. By so doing Iprevent the fines or tine sand from building up in the area in theformation 14 surrounding the well 18 and shutting off the oil fromventering the well 18. Thusly I welcome all the sand to now come into theoutput well 18 and by so doing I provide a free flow of oil and sandinto the output well 18 and I cause the oil and sand to be removed tothe surface simultaneously and continuously as fast as the sand comesinto the output well 18, and by so doing I get a surpringly increase inoil production over that of the conventional methods.

But in order to efliciently remove this sand and oil, which is in acommingled state, I have discovered that I have to provide a certainspecific velocity of fluid in the jet pump 17, or I should say in theventuri-tube located in the jet pump 17, or the jet pump will not worksatisfactory. The velocities which must be used are as follows:

In a 500 well the velocity of the power iiuid is about 19,560 feet perminute; and in a 1,000 foot oil well, the velocity of the power fluid isabout 27,350 feet per minute; and in a 2,000 foot oil well for example,the velocity of the power uid will be 33,900 feet per minute; and in a3,000 foot oil well, for example, the velocity of the power fluid willbe about 42,000 feet per minute.

I have used these said uid speeds in actual oil field tests and tindthem practical as applied to raising oil, water, and sand from deepdeposits in the earth.

An essential function in removing sand from deposits in the earth is tokeep the sand moving continuously from the formation 14, as contrary toan intermittent action such as is found in a conventional reciprocatingrod oil well pump.

This continuous sand entraining action serves to prevent quantities offme sand from building up as a barrier surrounding the output well 18and thusly shutting off the inward flow of oil thereto.

To lessen the abrasive action of the sand entrained into the jet pump 17and upon nozzle 52 thereof, I circulate four to tive volumes of clearhot water as a motivating fluid to intermingle with one volume of fluidentrained from the formation 14 and containing a large percentage oftine sand.

For example, the area of the orifices of nozzles 51 and 52 will be madesuch so that when thirty-live gallons of iiuid 1s being circulatedthrough the jet pump there will be seven to nine gallons per minuteentrained from the formation 14 into the annulus passage 20 of thesystem.

The above mentioned thirtyiive gallons per minute of .6 iluid is theiiuid used in the jet jump 17 as my motivating fluid or water and it isheated so that in addition to its entraining function, it is alsoutilized for heating the formation 14 and augments the ow of oil andtine sand into the output well 18. The pressure set up by the ow ofwater out 0f the input well 15 onto the formation 14 causes oil to bemoved in formation 14 toward and into output well 18 and it also causesloose sand to be moved together with the said oil. This heated wateralso augments the separation of the oil and water inV tank 1 in anefficient manner and by this action allows the water to be used overagain as the motivating medium to entrain oil, sand and interstitialwater from the formation 14 in a continuous and constant method ofproduction, through means of a closed system arranged to automaticallyfunction as a whole, as contrary to an inter-v mittent functional methodof recovery. An important function of this method is the provision forthe continuous and constant removal of sand out of output well 18 on thebasis of my findings that it is as equally important to provide for theabove described removal of sand in the production of oil as it is toprovide for the production of the natural oil. As'above stated thepresent conventional oil eld practice is to do everything possible tokeep the sand out of the output well, whereas in my new result I provideevery means to remove the sand out of the immediate'area surrounding theoutput well.

What I claim is:

l. A process for the secondary recovery of petroleum uids from asubterranean formation having therein an output well and an input wellspaced therefrom comprising: providing a continuous iiow of heatedliquid into and out of said output well thereby heating the formationadjacent the output well and the petroleum fluids therein, causing saidflowing liquid during its passage from said output well to How at alinear velocity suflicient to entrain therein and convey therewithpetroleum iiuids and entraining in said llowing uid and conveyingthereby petroleum fluids from said output well, withdrawing liquid mixedwith petroleum fluids from said flowing liquid during the passage of thelatter from said output well, introducing additional heated liquid intosaid flowing liquid during passage of the latter into the output well,introducing into said input well heated liquid at a suiiicient rate,temperature and pressure to thereby heat said formation between saidwells and the petroleum liuids therein and to drive a volume of saidpetroleum fluids into said output well, said steps of introducingheatedliquid into said input and output wells being performed to jointly causethe flow of petroleum uids from the formation into said output well.

2. A process for the secondary recovery of petroleum uids from asubterranean formation having therein an output well and an input wellspaced therefrom comprising: providing a continuous ow of heated liquidinto and out of said output well thereby heating the formation adjacentthe output well and the petroleum fluids therein, causing said flowingliquid during its passage from said output well to flow at a linearvelocity sufficient to entrain therein and convey therewith petroleumfluids and sand particles and entraining in said iiowing liquid andconveying thereby petroleum fluids and sand particles from said outputwell, withdrawing liquid mixed with petroleum uids and sand particlesfrom said flowing liquid during the passage of the latter from saidoutput well, introducing additional heated liquid into said flowingliquid during passage of the latter into the output well, introducinginto said input well heated liquid at a sutiicient rate, temperature andpressure to thereby heat said formation between said wells and thepetroleum fluids therein and to drive a volume of said petroleum fluidsinto said output well, said steps of introducing heated liquid into saidinput and output wells being performed to jointly cause the flow ofpetroleum fluids from the formation into said output well.

3. The process of claim.4 "1 wherein the liquid introduced intotheinputl and output wells isY at a tempera-- ture lofl atleast-230 F. and'the flowing liquidl andfth'e, withdrawn liquid removedV from said outputwellfis atl a temperature of about 200v F. i

4. The process of claim 1 wherein saidV linear velocity is at least19,000 feet per minute.

5. The process of claim 1` wherein.` said linear velocity rangesbetween- 19,000 and 42,000 feet per minute.

6. The process of'claim 1 wherein thfheatedfliquid i's introduced'intosaid output well at a, pressure exceed ing the hydrostatic pressureinsaid output well by from 1500 to 2500 poundsper square inch.

7. The process of' claim l wherein saidfcontinuousow of liquid in saidoutputl well is effected by continuous-r circulation of liquid in aclosed system.

8. A process for recovering` petroleum lluids from a subterraneanformation havingspaced output and input wells therein comprising:introducing into said input well a heated liquid at a rate, temperatureandy pressure sufcient to heat said formation between said wells and thepetroleum iluids therein and to driver the latter into said output well,continuously circulating into. and out of the output well in a vclosedsystem heated liquid ata presf sure in excess of the hydrostatic head ofthe output well thereby heating the formation adjacent the output welland the petroleum fluids therein, producing in said output well with aportion of sa-id`excess pressure ow of said circulatingliquid'at auaccelerated' linear velocity sufiicient to thereby entrain and conveytherewith petroleum uid'sirr said' output well; removing. from -saidaccelerated How of liquids'aid entraineduid's, introducing additional'heated liquidi into said circulating liquid in sufficient quan-- tityandpressure to-ieplace said removed fluids and to maintain saidlquantity and pressure of fluid `circulating in said'closed' system.

neferencesfcited in the me of thisv patent UNITED. STATES PATENTS OTHERREFERENCES Uren: Petroleum ProductionA Engineering Exploitation, secondedition, Pub. 1939 by McGraw-Hill, pp. 452 and 453'.

